Neurological symptoms worsen in about a third of stroke patients in the days after a stroke, says researcher Ángel Chamorro, M.D., of the Hospital Clínic, Clinical Institute of Nervous System Diseases, IDIBAPS, in Barcelona, Spain. This increases the risk of death and long-term disability. However, scientists know little about why.
In this study, researchers took blood samples from 231 ischemic stroke patients when they were admitted. Ischemic strokes are caused by a blood clot that blocks blood flow to the brain.
Researchers determined the blood levels of two natural anti-inflammatory cytokines: IL-10 and interleukin-4 (IL-4). The average time from stroke onset to admission was 8.2 hours. Samples were collected within 12 hours in 80 percent of patients and within 6 hours in 50 percent. Researchers also collected samples from 43 patients admitted to the hospital without neurological disorders. These people served as controls.
The researchers found that patients with low levels of IL-10 in their blood during the first hours after stroke were three times more likely to have worsening neurological symptoms.
"This relationship was independent of other well-known predictors of clinical worsening such as clinical severity on admission, elevated glucose, early signs of tissue damage or high fever. Overall, this study reinforces the growing evidence that anti-inflammatory processes play a major role in human acute ischemia and suggests that IL-10 may have a potential role as a neuroprotectant in acute vascular syndromes," Chamorro says.
While IL-10 levels were associated with stroke progression, there was no link between stroke progression and the level of IL-4, he says.
IL-10 plasma concentrations of less than 6 picograms per milliliter (pg/mL) were independently associated with clinical worsening within 48 hours. Eighty-three patients or 35.9 percent experienced a worsening of neurological symptoms.
"IL-10 appears to be especially significant in patients with small-vessel disease," Chamorro says.
However, it's too soon to suggest that IL-10 levels be used as part of a standard clinical evaluation of stroke patients, he says. "For the time being, measuring these molecules must be restricted to research protocols and clinical studies. While findings observed in this study are very fruitful for hypothesis generation, clinical practice still must rely on classical tools, such as neuro-imaging data and neurological examination."
However, Chamorro adds that patients with very low levels of IL-10 may be good candidates for studies of experimental drugs designed to protect brain cells. By taking baseline measurements, it may be possible to "select high-risk candidates for clinical trials in which neuro-protection relies on inflammation-mediated damage."
Co-authors are Nicolás Vila, M.D.; José Castillo, M.D.; Antonio Dávalos, M.D., Ph.D.; Anna Esteve, Ph.D.; and Ana M. Planas.
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